Gamma ray enhanced Vis-NIR photoluminescence and cytotoxicity of biocompatible silica coated Nd3+ doped GdPO4 nanophosphors

Abstract

Near infrared (NIR) emitting nanophosphors have a great potential for biomedical applications. Core nanoparticles of Nd3+ doped GdPO4@SiO2 with 3–6 nm sized spheres have been synthesized by solution combustion synthesis. The structure, morphology and luminescence properties of as synthesized nanophosphors have been examined by X-ray diffraction, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Photoluminescence spectra (PL). Upon photoexcitation at 532 nm, GdPO4:Nd3+@SiO2 emits red luminescence at 681 nm and NIR luminescence at 797 nm corresponding to 4F9/2 → 4I9/2 and 4F5/2 → 4I9/2 transitions, respectively. The luminescence intensity of nanophosphor had enhanced 2 folds on increasing the Nd3+ content from 1% to 5%. The luminescence intensity of these nanophosphors had further enhanced 2–3 folds and 8–10 folds after exposed to 150 kGy and 300 kGy of gamma radiation, respectively. In addition, this nanophosphor also exhibits high cytotoxicity against cell lines of PC-3 (Prostate cancer cells) and MCF-7 (Breast cancer cells).